Double ribbed cover

ABSTRACT

A unitary closure is used with a tubular container having an open end with a cylindrical connecting bead at the open end. The unitary closure comprises a planar circular wall defining a flat upper surface having a peripheral edge. A first concentric ring is radially outwardly of the peripheral edge defining a first upwardly opening valley. A second concentric ring is radially outwardly of the first concentric ring at an annular peak and defines a second upwardly opening valley having a generally planar bottom wall. Inner and outer concentric ribs extend downwardly from the planar bottom wall. A connecting flange is radially outwardly of the second concentric ring including a downwardly opening channel receivable on the cylindrical connecting bead to close the open end of the container. The closure has a substantially greater wall thickness radially outwardly of the peak than radially inwardly of the peak.

FIELD OF THE INVENTION

This invention relates to a drum closure and, more particularly, to a double ribbed cover of varying wall thickness.

BACKGROUND OF THE INVENTION

In one form of conventional shipping and storage container, a drum comprises a tubular container having an open end with a cylindrical connecting bead at the open end. The connecting bead may be provided by a metal connecting ring rolled onto the side wall or a plastic connecting ring molded directly to or otherwise adhered to the side wall. Alternatively, the side wall may be of molded plastic construction with an integral connecting bead.

The conventional drum includes a removable closure for closing the open end of the tubular side wall. A typical closure includes a central circular wall with a peripheral connecting flange receivable on the connecting bead so that the circular wall closes the open end of the container. A locking band secures the closure on the drum. While such a container may be used for storage purposes, often the containers must be lifted by lifting equipment and shipped, such as by truck. Various standards organizations require that a closure for use on a drum as described have suitable reinforcement to provide sufficient impact resistance. Typically, such a closure includes circular channels or rings formed in the circular wall providing a wave-like appearance. Also, the closures may include reinforcing ribs.

A typical closure is formed of molded synthetic resin, such as high density polyethylene. In designing such a closure, consideration may be given to minimizing weight and cost of the closure while also satisfying standards requirements. As such, a conventional closure is manufactured having a wall thickness sufficient for impact resistance. A typical closure for a 21½″ drum has a wall thickness on the order of 0.16″ nominal. As is known, the wall thickness may narrow to, for example, 0.15″ at the edges to provide draft for molding. Lesser thickness closures have been considered, but may not provide the necessary impact resistance.

The present invention is directed to solving one or more of the problems discussed above in a novel and simple manner.

SUMMARY OF THE INVENTION

In accordance with the invention, there is provided a closure for use with a tubular container including areas of different wall thickness.

Broadly, in accordance with one aspect of the invention, there is disclosed a unitary closure for use with a tubular container having an open end with a cylindrical connecting bead at the open end. The unitary closure comprises a planar circular wall defining a flat upper surface having a peripheral edge. A first concentric ring is radially outwardly of the peripheral edge defining a first upwardly opening valley. A second concentric ring is radially outwardly of the first concentric ring at an annular peak and defines a second upwardly opening valley having a generally planar bottom wall. Inner and outer concentric ribs extend downwardly from the planar bottom wall. A connecting flange is radially outwardly of the second concentric ring including a downwardly opening channel receivable on the cylindrical connecting bead to close the open end of the container. The closure has a substantially greater wall thickness radially outwardly of the peak than radially inwardly of the peak.

It is a feature of the invention that the closure comprises a wall thickness nominally about 0.16″ radially outwardly of the peak and a wall thickness nominally 0.09″ radially inwardly of the peak.

It is another feature of the invention that the circular wall and the first concentric ring have a first wall thickness, the second concentric ring, radially inwardly of the outer concentric rib has a second wall thickness greater than the first wall thickness and the outer concentric ring and the connecting flange have a third wall thickness greater than the second wall thickness.

It is still another feature of the invention that the closure has a wall thickness radially outwardly of the peak more than 50% greater than radially inwardly of the peak.

It is still another feature of the invention that the closure has a wall thickness radially outwardly of the peak about two-thirds greater than radially inwardly of the peak.

There is disclosed in accordance with another aspect of the invention a unitary closure for use with a tubular container having an open end with a cylindrical connecting bead at the open end. The unitary closure comprises a downwardly opening U-shaped wall portion receivable on the cylindrical connecting bead. A concentric ring is inwardly of the U-shaped wall portion defining an upwardly opening valley including an outer wall connected to the U-shaped wall portion, a planar bottom wall and a conical inner wall having an upper annular edge. Inner and outer concentric ribs extend downwardly from the planar bottom wall. A circular center wall is connected to the upper annular edge. The closure has a substantially greater wall thickness radially outwardly of the upper annular edge than radially inwardly of the upper annular edge.

It is a feature of the invention that the center wall comprises a planar circular wall defining a flat upper surface having a peripheral edge and another concentric ring radially outwardly of the peripheral edge, defining another upwardly opening valley, and connected to the upper annular edge.

It is a further feature of the invention to provide a pair of recessed bung wells connected to the center wall radially inwardly of the inner concentric rib.

It is still another feature of the invention that the U-shaped wall portion has a diameter to be received and a tubular container having a 21½″ connecting bead.

It is still a further feature of the invention that the closure comprises a unitary wall element of synthetic resin.

Further features and advantages of the invention will be readily apparent from the specification and from the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded perspective view of a container including a closure according to the invention;

FIG. 2 is a top perspective view of the closure of FIG. 1;

FIG. 3 is a bottom perspective view of the closure of FIG. 1;

FIG. 4 is a sectional view taken along a line 4-4 of FIG. 2;

FIG. 5 is a detailed sectional view of a left portion of the sectional view of FIG. 4; and

FIG. 6 is a sectional view illustrating the assembled container and closure.

DETAILED DESCRIPTION OF THE INVENTION

In the illustrated embodiment of the invention, as disclosed in FIG. 1, a shipping and storage container in the form of a drum 12 includes a tubular side wall 14 closed by a bottom wall (not shown) and having an open end 16 to define an interior space 18. A cylindrical connecting bead 20 is at the open end 16. The open end 16 is selectively closed by a closure 22 in accordance with the invention removably secured to the connecting bead 20 with a locking band 24.

In the illustrated embodiment of the invention, the drum 12 comprises a cylindrical, blow-molded plastic drum. The drum has a capacity of 55 U.S. gallons and the connecting bead 20 has a diameter of about 21½″. However, the present invention is directed particularly to the closure 22 which can be used with drums of other construction, such as metal, fiberboard, or composite construction, as will be apparent.

Referring to FIGS. 2-5, the closure 22 is illustrated in greater detail. The closure 22 comprises a unitary wall element of molded synthetic resin, such as high density polyethylene. The closure 22 includes a circular center wall 26. The center wall 26 comprises a circular planar wall or panel 28 surrounded by a first concentric ring 34. The circular panel 28 has a flat upper surface 30 having a peripheral edge 32. The first concentric ring 34 is radially outwardly of the peripheral edge 32 defining a first upwardly opening valley 36. Particularly, the first concentric ring is generally V-shaped. A second concentric ring 38 is radially outwardly of the first concentric ring 34. The concentric rings 34 and 38 are connected at an annular peak 40. The second concentric ring 38 defines a second upwardly opening valley 42. The second upwardly opening valley 42 is more U-shaped having a generally flat bottom. Particularly, the second concentric ring 38 includes an outer wall 44, a planar bottom wall 46 and a conical inner wall 48. An upper annular edge of the conical inner wall 48 comprises the annular peak 40 connected to the first concentric 34. The concentric rings 34 and 38 provide a wave like appearance. An inner concentric rib 50 extends downwardly from the bottom wall 46 at its junction with the conical wall 48. An outer concentric rib 52 extends downwardly from the bottom wall 46 at its junction with the outer wall 44. The concentric ribs 50 and 52 are of similar height and are used to increase stiffness.

A connecting flange 54 is radially outwardly of the second concentric ring 38. The connecting flange 54 comprises a downwardly opening U-shaped wall portion 56 connected at an upper edge of the outer wall 44. The U-shaped wall portion defines a downwardly opening channel 58 receivable on the cylindrical connecting bead 20 to close the open end 16 of the container 12. Particularly, and with reference to FIG. 6, an annular gasket 60 is positioned in the channel 58. The gasket 60 is seated on the connecting bead 20. The locking band 24 sandwiches the connecting flange 54, gasket 60 and connecting bead 20 to retain the closure 22 on the drum 12 in a conventional manner.

In accordance with the invention, the closure 22 is adapted to use a reduced wall thickness in non-critical areas, while maintaining a standard wall thickness in critical areas.

Particularly, and with reference to FIGS. 4 and 5, the walls of the connecting flange 54 are shown to include a wall thickness A. The outer concentric rib 52 is also of the wall thickness A. The bottom wall 46, inner concentric rib 50 and conical wall 48 are of a wall thickness B. The annular peak 40, first concentric ring 34 and the circular planar wall 28 are of a wall thickness C. In accordance with the invention, the wall thickness A is substantially greater than the wall thickness C. The wall thickness B may be the same as the wall thickness A, or may be slightly less than the wall thickness A to provide a transition between the wall thickness A and the wall thickness C. Particularly, in accordance with the invention, the wall thickness A is more than 50% greater than the wall thickness C and in one embodiment of the invention is about two-thirds greater than the wall thickness C. In an illustrative embodiment of the invention, the wall thicknesses A and B are nominally 0.16″ and the wall thickness C is 0.09″. As will be apparent, the wall thickness at edges of the U-shaped wall portion 56 and the ribs 50 and 52 may be on the order of 0.15″ to provide draft for mold purposes. Alternatively, for transition purposes, the wall thickness B may be on the order of 0.13″ nominally. In either case, the wall thickness radially outwardly of the annular peak 40 is of substantially greater wall thickness than radially inwardly of the annular peak 40. The use of a substantially thicker wall thickness as described provides a lighter weight closure while maintaining required reinforcement in critical areas. In fact, a conventional closure of 0.16″ wall thickness has a weight of about 2.8 lbs. while the described closure has a weight of about 2.25 lbs.

Referring again to FIGS. 2 and 3, a pair of recessed bung wells 62 and 64 are connected to the center wall 28 radially inwardly of the inner concentric rib 40 and the planar bottom wall 46. The bung wells 62 and 64 may be provided with conventional bung or vent openings. The bung wells are of the thickness A, described above.

Thus, in accordance with the invention, there is provided a unitary double ribbed cover including reduced wall thickness in non-critical areas to reduce weight. 

I claim:
 1. A unitary closure for use with a tubular container having an open end with a cylindrical connecting bead at the open end, the unitary closure comprising: a planar circular wall defining a flat upper surface having a peripheral edge, a first concentric ring radially outwardly of the peripheral edge defining a first upwardly opening valley, a second concentric ring radially outwardly of the first concentric ring at an annular peak and defining a second upwardly opening valley having a generally planar bottom wall, inner and outer concentric ribs extending downwardly from the planar bottom wall, and a connecting flange radially outwardly of the second concentric ring including a downwardly opening channel receivable on the cylindrical connecting bead to close the open end of the container, the closure having a substantially greater wall thickness radially outwardly of the peak than radially inwardly of the peak.
 2. The unitary closure of claim 1 wherein the closure comprises a wall thickness nominally about 0.16 inches radially outwardly of the peak and a wall thickness nominally 0.09 inches radially inwardly of the peak.
 3. The unitary closure of claim 1 wherein the circular wall and the first concentric ring have a first wall thickness, the second concentric ring, radially inwardly of the outer concentric rib has a second wall thickness greater than the first wall thickness and the outer concentric rib and the connecting flange have a third wall thickness greater than the second wall thickness.
 4. The unitary closure of claim 1 wherein the closure having a wall thickness radially outwardly of the peak more than 50% greater then radially inwardly of the peak.
 5. The unitary closure of claim 1 wherein the closure having a wall thickness radially outwardly of the peak about ⅔ greater then radially inwardly of the peak.
 6. A unitary closure for use with a tubular container having an open end with a cylindrical connecting bead at the open end, the unitary closure comprising: a downwardly opening U-shaped wall portion receivable on the cylindrical connecting bead; a concentric ring inwardly of the U-shaped wall portion defining an upwardly opening valley including an outer wall connected to the U-shaped wall portion, a planar bottom wall and a conical inner wall having an upper annular edge; inner and outer concentric ribs extending downwardly from the planar bottom wall; and a circular center wall connected to the upper annular edge, the closure having a substantially greater wall thickness radially outwardly of the upper annular edge than radially inwardly of the upper annular edge.
 7. The unitary closure of claim 6 wherein the closure comprises a wall thickness nominally about 0.16 inches radially outwardly of the upper annular edge and a wall thickness nominally 0.09 inches radially inwardly of the upper annular edge.
 8. The unitary closure of claim 6 wherein the center wall has a first wall thickness, the concentric ring, radially inwardly of the outer concentric rib has a second wall thickness greater than the first wall thickness and the outer concentric rib and the U-shaped wall portion have a third wall thickness greater than the second wall thickness.
 9. The unitary closure of claim 6 wherein the closure having a wall thickness radially outwardly of the upper annular edge more than 50% greater then radially inwardly of the upper annular edge.
 10. The unitary closure of claim 6 wherein the closure having a wall thickness radially outwardly of the upper annular edge about ⅔ greater then radially inwardly of the upper annular edge.
 11. The unitary closure of claim 6 wherein the center wall comprises a planar circular wall defining a flat upper surface having a peripheral edge and another concentric ring radially outwardly of the peripheral edge, defining another upwardly opening valley, and connected to the upper annular edge.
 12. The unitary closure of claim 6 further comprising a pair of recessed bung wells connected to the center wall radially inwardly of the inner concentric rib.
 13. The unitary closure of claim 6 wherein the U-shaped wall portion has a diameter to be received on a tubular container having a 21½ inch connecting bead.
 14. The unitary closure of claim 6 wherein the closure comprises a unitary wall element of synthetic resin. 